Stability shifts at 300°C and 400°C stemmed from the substantial reconfiguration of the crystalline structure. A transition in the crystal structure's arrangement triggers increased surface roughness, greater interdiffusion, and the creation of compounds.
Many satellites, employing reflective mirrors for imaging, have focused on the auroral bands of N2 Lyman-Birge-Hopfield, whose emission lines are found between 140-180 nm. Excellent out-of-band reflection suppression and high reflectance at operating wavelengths are crucial for achieving good imaging quality in the mirrors. Mirrors composed of non-periodic multilayer LaF3/MgF2, which were designed and fabricated by our team, exhibit operational wave bands of 140-160 nm and 160-180 nm, respectively. Nevirapine nmr The multilayer was designed using a method that incorporated match design and a deep search method. The new Chinese wide-field auroral imager has integrated our work, leading to a diminished requirement for transmissive filters in the space payload's optics thanks to the remarkable out-of-band suppression of the implemented notch mirrors. Additionally, our investigation has established new avenues for the development of reflective mirrors for use in the far ultraviolet region.
Large field of view and high resolution are simultaneously achievable with lensless ptychographic imaging, presenting a significant advantage in compactness, mobility, and cost when compared to traditional lensed imaging systems. However, imaging systems without lenses are more susceptible to environmental distractions and capture images with lower resolution than lens-based systems, consequently increasing the time needed for a high-quality outcome. To address the challenges of convergence rate and noise in lensless ptychographic imaging, this paper proposes an adaptive correction method. This method leverages adaptive error and noise correction terms within the algorithms, aiming for faster convergence and improved suppression of both Gaussian and Poisson noise. The Wirtinger flow and Nesterov algorithms are used in our method to minimize computational complexity and enhance the rate of convergence. Phase reconstruction in lensless imaging was tackled using our method, the efficacy of which was substantiated by simulation and experimental data. The method's application to other ptychographic iterative algorithms is uncomplicated.
Obtaining high spectral resolution and high spatial resolution in measurement and detection concurrently has been a longstanding impediment. Our measurement system, based on single-pixel imaging with compressive sensing, accomplishes excellent spectral and spatial resolution at once, and effectively compresses data. Our method excels in achieving both high spectral and spatial resolution, a characteristic distinct from the inherent trade-off between these two factors in conventional imaging techniques. Within the scope of our experimental work, 301 spectral channels were collected from the 420-780 nm band, boasting a spectral resolution of 12 nm and a spatial resolution of 111 milliradians. Employing compressive sensing, a 125% sampling rate for a 6464p image is achieved, simultaneously decreasing measurement time and enabling concurrent high spectral and spatial resolution despite the lower sampling rate.
Continuing a pattern from the Optica Topical Meeting on Digital Holography and 3D Imaging (DH+3D), this feature issue is a direct result of the meeting's conclusions. Current research topics in digital holography and 3D imaging, aligned with Applied Optics and Journal of the Optical Society of America A, are addressed.
For large field-of-view observations in space x-ray telescopes, micro-pore optics (MPO) have been implemented. X-ray focal plane detectors with visible photon detection capabilities rely on the optical blocking filter (OBF) embedded in MPO devices to prevent any signal contamination resulting from visible photons. Our current work involves the construction of an instrument to determine light transmission with high accuracy. Measurements of MPO plate transmittance align with the design specifications, registering values that are all less than 510-4. Applying the multilayer homogeneous film matrix methodology, we assessed likely alumina film thickness pairings that harmonized well with the specifications of the OBF design.
Jewelry appraisal and identification are constrained by the interference of adjacent gemstones and the metal mount. This research proposes imaging-assisted Raman and photoluminescence spectroscopy as a method for jewelry measurement, thus promoting transparency in the jewelry market. The system, referencing the image for alignment, can automatically measure multiple gemstones on a jewelry piece in a sequential order. The experimental prototype showcases the ability to noninvasively distinguish natural diamonds from their laboratory-created and imitation counterparts. Besides this, the image facilitates the process of evaluating gemstone color and estimating its weight.
For numerous commercial and national security sensing systems, low-lying clouds, fog, and other highly diffusive environments represent a significant obstacle. Nevirapine nmr Highly scattering environments pose a challenge to the performance of optical sensors, indispensable for autonomous systems' navigation. Earlier simulations from our work indicated the potential of polarized light to propagate through a scattering environment similar to fog. We have established that circularly polarized light remains more faithful to its initial polarization than linearly polarized light, enduring countless scattering events and thus far-reaching distances. Nevirapine nmr This finding has been experimentally validated by other researchers recently. We detail the design, construction, and testing of active polarization imagers operating at visible and short-wave infrared wavelengths in this work. Polarimetric configurations of imagers, focusing on linear and circular polarization, are examined in multiple ways. Under realistic fog conditions, the polarized imagers were subjected to testing at the Sandia National Laboratories Fog Chamber. Active circular polarization imagers demonstrate superior range and contrast enhancement in foggy conditions compared to linear polarization imagers. Circularly polarized imaging, when applied to typical road sign and safety retro-reflective films, displays an improved contrast in different fog conditions compared to linear polarization. This improvement translates to a deeper penetration of fog by 15 to 25 meters, surpassing linearly polarized imaging's reach, underscoring the critical dependence on the polarization's interaction with the target.
The real-time monitoring and closed-loop control of laser-based layered controlled paint removal (LLCPR) from aircraft skin is foreseen to utilize laser-induced breakdown spectroscopy (LIBS). In contrast to alternative methods, the LIBS spectrum's analysis must be performed rapidly and accurately, and the monitoring protocol should be based on machine learning algorithms. This study constructs a bespoke LIBS monitoring system for paint removal, employing a high-frequency (kilohertz-level) nanosecond infrared pulsed laser. It collects LIBS spectra during the laser-induced removal of the top coating (TC), primer (PR), and aluminum substrate (AS). The continuous background of the spectrum was removed, and key features were extracted. This enabled the construction of a classification model for three spectral types (TC, PR, and AS) using a random forest algorithm. An experimental verification followed the establishment of a real-time monitoring criterion, using this classification model and multiple LIBS spectra. The results pinpoint a classification accuracy of 98.89%. The time taken for classification on each spectrum averages around 0.003 milliseconds. Monitoring of the paint removal process demonstrates conformity with the macroscopic and microscopic analyses of the samples. Overall, the research provides essential technical support for continuous monitoring and closed-loop control of LLCPR signals emanating from the aircraft's hull.
When experimental photoelasticity images are captured, the spectral interplay between the light source and the sensor used alters the visual information seen in the fringe patterns of the resulting images. Fringe patterns of excellent quality are a possibility with this interaction, but it can also lead to images with blurred fringes and flawed stress field reconstructions. To evaluate these interactions, a strategy using four tailored descriptors is presented: contrast, an image descriptor accounting for both blur and noise, a Fourier descriptor to assess image quality, and image entropy. The utility of the proposed strategy was established by measuring the selected descriptors in computational photoelasticity images, with the evaluation of the stress field across 240 spectral configurations, using 24 light sources and 10 sensors, revealing achieved fringe orders. High values of the chosen descriptors were observed to correlate with spectral patterns that enhance the reconstruction of the stress field. The findings generally indicate that the selected descriptors are capable of differentiating between positive and negative spectral interactions. This differentiation has the potential to improve the design of photoelasticity image acquisition protocols.
The petawatt laser complex PEARL now includes a newly developed front-end laser system with an optical synchronization feature for both chirped femtosecond and pump pulses. The PEARL's parametric amplification stages now exhibit enhanced stability, thanks to the new front-end system's broader femtosecond pulse spectrum and the temporal shaping of the pump pulse.
Daytime slant visibility measurements are significantly influenced by atmospheric scattered radiance. This paper scrutinizes the impact of atmospheric scattered radiance errors on the accuracy of slant visibility measurements. Recognizing the difficulties in simulating errors stemming from the radiative transfer equation, an error simulation methodology, grounded in the Monte Carlo method, is proposed.